Development of a SARS-CoV-2 Total Antibody Assay and the Dynamics of Antibody Response over Time in Hospitalized and Nonhospitalized Patients with COVID-19

Abstract

Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infections often cause only mild disease that may evoke relatively low Ab titers compared with patients admitted to hospitals. Generally, total Ab bridging assays combine good sensitivity with high specificity. Therefore, we developed sensitive total Ab bridging assays for detection of SARS-CoV-2 Abs to the receptor-binding domain (RBD) and nucleocapsid protein in addition to conventional isotype-specific assays. Ab kinetics was assessed in PCRconfirmed, hospitalized coronavirus disease 2019 (COVID-19) patients (n = 41) and three populations of patients with COVID-19 symptoms not requiring hospital admission: PCR-confirmed convalescent plasmapheresis donors (n = 182), PCR-confirmed hospital care workers (n = 47), and a group of longitudinally sampled symptomatic individuals highly suspect of COVID-19 (n = 14). In nonhospitalized patients, the Ab response to RBD is weaker but follows similar kinetics, as has been observed in hospitalized patients. Across populations, the RBD bridging assay identified most patients correctly as seropositive. In 11/14 of the COVID-19-suspect cases, seroconversion in the RBD bridging assay could be demonstrated before day 12; nucleocapsid protein Abs emerged less consistently. Furthermore, we demonstrated the feasibility of finger-prick sampling for Ab detection against SARS-CoV-2 using these assays. In conclusion, the developed bridging assays reliably detect SARS-CoV-2 Abs in hospitalized and nonhospitalized patients and are therefore well suited to conduct seroprevalence studies.

Comprehensive analysis of SARS-CoV-2 antibody dynamics in New Zealand

“…Overall, this study provides a comprehensive view of SARS-CoV-2 antibodies over eight months. The strong correlation between anti-RBD IgG and NAbs, combined with the demonstration in this study and by others 4,25,30 that anti-RBD can reliably be measured from dried blood fingerpick samples, provides feasibility for future SARS-CoV-2 immunokinetic studies that incorporate RBD-IgG based assays. The importance of conducting such studies at scale during vaccine roll-out is particularly relevant in settings like New Zealand, where there is potential to gain novel insight on vaccine responses given the lack of circulating SARS-CoV-2 in the community.…”

Comprehensive analysis of SARS‐CoV‐2 antibody dynamics in New Zealand

“…Overall, this study provides a comprehensive view of SARS-CoV-2 antibodies over 8 months. The strong correlation between anti-RBD IgG and NAbs, combined with the demonstration in this study and by others 4,25,30 that anti-RBD can reliably be measured from dried blood fingerpick samples, provides feasibility for future SARS-CoV-2 immunokinetic studies that incorporate RBD IgGbased assays. The importance of conducting such studies at scale during vaccine roll-out is particularly relevant in settings such as New Zealand, where there is potential to gain novel insight on vaccine responses given the lack of circulating SARS-CoV-2 in the community.…”

Dynamics of antibodies to SARS-CoV-2 in convalescent plasma donors

“…Total antibody, IgM and IgA to RBD was measured as described previously [9]. IgG to RBD and NP were measured essentially as described before [9], but with several modifications. RBD and NP proteins were produced as described in Vogelzang et al ., [9].…”

“…IgG to RBD and NP were measured essentially as described before [9], but with several modifications. RBD and NP proteins were produced as described in Vogelzang et al ., [9]. IgG1 and IgG3 subclasses were detected by adding 0.5 µg/mL HRP-conjugated monoclonal mouse antihuman IgG1 (MH161.1, Sanquin) or 1.0 µg/mL antihuman IgG3 (MH163.1, Sanquin) diluted in PBS supplemented with 0.02% polysorbate-20 and 0.3% gelatin) (PTG) for 30 minutes.…”

“…Virtually all PCR-confirmed patients develop IgM, IgA and IgG antibodies against the virally encoded surface glycoproteins spike (S) and nucleocapsid protein (NP) [9][10][11]. The S protein mediates binding of the virus particle to angiotension converting enzyme-2 (ACE2) on target cells through its receptor binding domain (RBD) [12,13], enabling merging of viral and target cell membrane.…”